The present invention relates to movable microstructure methods and apparatus. Movable microstructures may be used in many different applications. For example, certain movable microstructures may be used to implement large-port-count optical crossbar switches which facilitate the flow of data over a computer network (e.g., the Internet).
The explosive growth of internet traffic in the last few years, and its unabated continuation into the foreseeable future, has created an unprecedented demand on the communication infrastructure of both long distance and interchange carriers. The term “fiber exhaust” was coined in the last few years to describe the saturation of traffic in the present installed base of optical fibers. Thus ushered in the era of wavelength division multiplex (WDM), a technique for using multiple colors of light inside a single strand of fiber in order to boost the capacity of the fiber manifold without actually having to install any new fibers. But as internet traffic continues to grow, the fiber-optic network infrastructure is encountering another bottleneck which WDM or similar solutions cannot solve. Interconnection between the growing number of channels supported by WDM systems demands solutions based on optical-cross-connects (OXCs). Large-port-count optical crossbar switches promise to be key components for performing OXC functions.
An optical crossbar switch can provide interchange of data paths between different fibers, at multi-gigabit data rates, without having to first convert them into the electronic domain as is being done in existing networks. An N×N optical crossbar switch consists of N input and N output optical fiber ports, with the capability of selectively directing light from any input port to any output port in a “non-blocking” fashion. Currently, switches deployed in the communication infrastructure operate by converting the input optical signals to electronic signals, directing the electronic signals to the proper output channels, and converting them back into optical signals. In an all-optical OXC, the light is directly deflected from an input fiber port into an output fiber port without any electrical conversion. Each of the optical beams can be expanded and collimated by inserting a microlens at the tip of each input and output fiber port. By propagating an array of optical beams in free space and selectively actuating reflectors in an array of movable reflectors, any one of the N input optical beams can be directed to any one of the N output fibers ports. The core of each input and output fiber port is the region in which most of the optical beam travels. Due to the small diameter of the core, the optical crossbar switch requires the reflectors to be maintained at a precise position in order to direct each optical beam from one fiber port to another.
The optical crossbar switch has several inherent advantages over its electronic counterpart, including data rate, format, wavelength independence, and lower costs. Furthermore, with advances in microelectromechanical systems (MEMS) technology, batch processing and assembly methods similar to those used in the IC industry can be employed to produce optical crossbar switches with high port-counts at very low costs.